Objective C 内存泄漏

Question

这里有两个方法返回我的自定义四属性对象的字典。他们创建字符串、浮点数和 BOOL 数组来放入 Chemical 对象，然后根据数组构建字典。我对整个内存管理游戏还很陌生，我并不总是确定我何时拥有某些东西以及何时释放它。我正在即时制作各种琴弦。

事情是这样的：静态分析器认为第一个方法 - (id)generateChlorineDictionary 没有问题，但说第二个方法 - (id)generateCYADictionary 存在泄漏。它说它从 NSMutableArray *cyaGranulesArray... 开始，然后转到 NSDictionary *cyaDictionary... ，最后到 return cyaDictionary 语句。

这是两种方法；抱歉，它们太长了！

---

编辑：将名称从generateChlorineDictionary更改为newChlorineDictionary
删除了返回后发生的发布

- (id)newChlorineDictionary {
// Sets up the array for the Bleach key
    NSMutableArray *bleachArray = [[NSMutableArray alloc] init]; 
    NSArray *bleachConcentrationArray = [[NSArray alloc] initWithObjects:@"6%", @"10%", @"12%", nil];
    float bleachConstantArray[] = {0.0021400, 0.0012840, 0.0010700};
    for (int i=0; i<3; i++) {
        Chemical *bleachChemical = [[Chemical alloc] initWithChemical:@"Bleach" 
                                                andConcentration:[bleachConcentrationArray objectAtIndex:i] 
                                                     andConstant:bleachConstantArray[i] 
                                                     andIsLiquid:YES];
        [bleachArray addObject:bleachChemical];
        NSLog(@"bleachChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", bleachChemical.chemName, bleachChemical.chemConcentration, bleachChemical.chemConstant, bleachChemical.chemIsLiquid);
        [bleachChemical release];
    }
    bleachConcentrationArray = nil;
// Sets up the array for the Trichlor key   
    NSMutableArray *trichlorArray = [[NSMutableArray alloc] init];
    Chemical *trichlorChemical = [[Chemical alloc] initWithChemical:@"Trichlor" 
                                            andConcentration:@"90%" 
                                                 andConstant:0.0001480
                                                 andIsLiquid:NO];
    [trichlorArray addObject:trichlorChemical];
    NSLog(@"trichlorChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", trichlorChemical.chemName, trichlorChemical.chemConcentration, trichlorChemical.chemConstant, trichlorChemical.chemIsLiquid);
    [trichlorChemical release];
// Sets up the array for the Dichlor key
    NSMutableArray *dichlorArray = [[NSMutableArray alloc] init]; 
    NSArray *dichlorConcentrationArray = [[NSArray alloc] initWithObjects:@"56%", @"62%", nil];
    float dichlorConstantArray[] = {0.0002400, 0.0002168};
    for (int i=0; i<2; i++) {
        Chemical *dichlorChemical = [[Chemical alloc] initWithChemical:@"Dichlor" 
                                                andConcentration:[dichlorConcentrationArray objectAtIndex:i] 
                                                     andConstant:dichlorConstantArray[i] 
                                                     andIsLiquid:NO];
        [dichlorArray addObject:dichlorChemical];
        NSLog(@"dichlorChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", dichlorChemical.chemName, dichlorChemical.chemConcentration, dichlorChemical.chemConstant, dichlorChemical.chemIsLiquid);
        [dichlorChemical release];
    }
    dichlorConcentrationArray = nil;
// Sets up the array for the Cal Hypo key
    NSMutableArray *calHypoArray = [[NSMutableArray alloc] init]; 
    NSArray *calHypoConcentrationArray = [[NSArray alloc] initWithObjects:@"48%", @"53%", @"65", @"73", nil];
    float calHypoConstantArray[] = {0.0002817, 0.0002551, 0.0002080, 0.0001852};
    for (int i=0; i<2; i++) {
        Chemical *calHypoChemical = [[Chemical alloc] initWithChemical:@"Cal Hypo" 
                                                andConcentration:[calHypoConcentrationArray objectAtIndex:i] 
                                                     andConstant:calHypoConstantArray[i] 
                                                     andIsLiquid:NO];
        [calHypoArray addObject:calHypoChemical];
        NSLog(@"calHypoChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", calHypoChemical.chemName, calHypoChemical.chemConcentration, calHypoChemical.chemConstant, calHypoChemical.chemIsLiquid);
        [calHypoChemical release];
    }
    calHypoConcentrationArray = nil;
// Sets up the array for the Li Hypo key    
    NSMutableArray *liHypoArray = [[NSMutableArray alloc] init];
    Chemical *liHypoChemical = [[Chemical alloc] initWithChemical:@"Li Hypo" 
                                            andConcentration:@"90%" 
                                                 andConstant:0.0003800
                                                 andIsLiquid:NO];
    [liHypoArray addObject:liHypoChemical];
    NSLog(@"liHypoChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", liHypoChemical.chemName, liHypoChemical.chemConcentration, liHypoChemical.chemConstant, liHypoChemical.chemIsLiquid);
    [liHypoChemical release];
// The array of keys for the chlorine chemicals
    NSArray *chlorineKeys = [[NSArray alloc] initWithObjects:@"Bleach", @"Trichlor", @"Dichlor", @"Cal Hypo", @"Li Hypo", nil];
// The array of values for the chlorine chemicals
    NSArray *chlorineValues = [[NSArray alloc] initWithObjects:bleachArray, trichlorArray, dichlorArray, calHypoArray, liHypoArray, nil];
    [bleachArray release];
    [trichlorArray release];
    [dichlorArray release];
    [calHypoArray release];
    [liHypoArray release];
// The dictionary to hold the arrays of chlorine chemical objects
    NSDictionary *chlorineDictionary = [[NSDictionary alloc] initWithObjects:chlorineValues forKeys:chlorineKeys];
    [chlorineValues release];
    [chlorineKeys release];
    return chlorineDictionary;
}

---

编辑：将名称从generateCYADictionary更改为newCYADictionary
删除了返回后发生的发布

- (id)newCYADictionary {
    // Sets up the array for the CYA Granules key   
    NSMutableArray *cyaGranulesArray = [[NSMutableArray alloc] init];
    Chemical *cyaGranulesChemical = [[Chemical alloc] initWithChemical:@"CYA Granules" 
                                                   andConcentration:@"" 
                                                        andConstant:0.0001330
                                                        andIsLiquid:NO];
    [cyaGranulesArray addObject:cyaGranulesChemical];
    NSLog(@"cyaGranulesChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", cyaGranulesChemical.chemName, cyaGranulesChemical.chemConcentration, cyaGranulesChemical.chemConstant, cyaGranulesChemical.chemIsLiquid);
    [cyaGranulesChemical release];
    // Sets up the array for the Liquid Stabilizer key  
    NSMutableArray *liquidStabilizerArray = [[NSMutableArray alloc] init];
    Chemical *liquidStabilizerChemical = [[Chemical alloc] initWithChemical:@"Liquid Stabilizer" 
                                                 andConcentration:@"" 
                                                      andConstant:0.0003460
                                                      andIsLiquid:YES];
    [liquidStabilizerArray addObject:liquidStabilizerChemical];
    NSLog(@"liquidStabilizerChemical: chemName = %@, chemConcentration = %@, chemConstant = %1.6f, chemIsLiquid = %d", liquidStabilizerChemical.chemName, liquidStabilizerChemical.chemConcentration, liquidStabilizerChemical.chemConstant, liquidStabilizerChemical.chemIsLiquid);
    [liquidStabilizerChemical release];
    // The array of keys for the CYA chemicals
    NSArray *cyaKeys = [[NSArray alloc] initWithObjects:@"CYA Granules", @"Liquid Stabilizer", nil];
    // The array of values for the CYA chemicals
    NSArray *cyaValues = [[NSArray alloc] initWithObjects:cyaGranulesArray, liquidStabilizerArray, nil];
    [cyaGranulesArray release];
    [liquidStabilizerArray release];
    // The dictionary to hold the arrays of CYA chemical objects
    NSDictionary *cyaDictionary = [[NSDictionary alloc] initWithObjects:cyaValues forKeys:cyaKeys]; 
    [cyaKeys release];
    [cyaValues release];
    return cyaDictionary;
}

Answer 1

替换

return cyaDictionary;
[cyaDictionary release];

为

return [cyaDictionary autorelease];

或者，您可以替换

NSDictionary *chlorineDictionary = [[NSDictionary alloc] initWithObjects:chlorineValues forKeys:chlorineKeys];

为

NSDictionary *chlorineDictionary = [NSDictionary dictionaryWithObjects:chlorineValues forKeys:chlorineKeys];

而不是添加autorelease。

在您的原始实现中，[cyaDictionary release]; 永远不会执行（因为它是在 return 之后）。

您可以在此方法之外使用该字典，并且不应在那里释放它。

您可能还想返回一个保留的对象（不带 autorelease）并在方法外释放它。在这种情况下，您应该以“new”或“alloc”开头方法名称......

编辑（重要）：
您应该只使用我的建议之一。

• 在 return 行中使用 autorelease
• 使用 dictionaryWith...
• 添加“new方法名称中添加“或”alloc”前缀，并在此方法之外释放返回的对象。

如果将 alloc init 替换为 dictionaryWith...，那么您将获得一个自动释放的对象。然后，如果您在外部方法中释放它，那么您就会遇到严重的问题（该对象将在线程的当前运行循环之后尝试释放自身，并且可能会使应用程序崩溃，因为该对象已经被您释放了）。

编辑（由于其中一条评论）
如果您想创建一个将返回字典的属性：

// MyClass.h file
@interface MyClass : NSObject {

    ..

    NSDictionary *_dict1;

    ..

}

@property (nonatomic, retain) NSDictionary *dict1;

..

@end

// MyClass.m file

@implementation MyClass

@synthesize dict1 = _dict1;

..

- (NSDictionary *)dict1 {
    if (_dict1 == nil) {
        NSDictionary *dict1Temp = [NSDictionary new];

        // Your implementation goes here...

        self.dict1 = dict1Temp;
        [dict1Temp release];
    }
}

..

- (void)dealloc {
    [_dict1 release];
    [suoer dealloc];
}

@end